In Long Term Evolution (LTE) communications technology, duplex modes may be classified into two types, Frequency Division Duplex (FDD) and Time Division Duplex (TDD). In the FDD mode, different frequencies are used in uplink and downlink channels, and frames of fixed time lengths are used for both uplink transmission and downlink transmission. In the TDD mode, uplink transmission and downlink transmission are performed in different timeslots, and usually share a same frequency. Compared with FDD, TDD has characteristics of high frequency utilization and flexible uplink and downlink resource configuration.
A carrier aggregation (CA) technology is a key technology in LTE, and is used to implement aggregation of carriers at two frequencies. Generally, the carrier aggregation technology may be implemented by using a radio frequency circuit of a terminal. According to different aggregation modes, carrier aggregation may be classified into three types: intra-band contiguous carrier aggregation, intra-band non-contiguous carrier aggregation, and inter-band carrier aggregation. Usually, the intra-band contiguous carrier aggregation is applicable to a scenario of narrow frequency spacing, and a radio frequency circuit structure thereof is simple; the intra-band non-contiguous carrier aggregation and inter-band carrier aggregation are applicable to a scenario of wide frequency spacing. Since frequency resources vary across global communications markets, the carrier aggregation technology is evolved with one of its focuses placed on promoting the capability of a radio frequency circuit to support wider frequency spacing.
In the prior art, in the TDD mode, two different bands in inter-band carrier aggregation are both used to transmit uplink signals or both used to receive downlink signals in a TDD timeslot, and consequently, the uplink and downlink resource configurations are inflexible.